The present invention relates to motor vehicle door locks and more particularly to electrically locked locks.
Such locks comprise, as is known, a forked latch intended to interact with a striker, a pawl which normally locks the latch in the closed position, a latch-release mechanism comprising an operating member which experiences an actuating movement in response to actuation of the door handle by the user. The operating member can adopt an active position in which it acts, during its actuating movement, on the pawl in order to place it in the escapement position, and an inhibited position in which, during its actuating movement, it has no effect on the pawl. The lock further comprises an electric device which responds at least to an unlock signal by moving the operating member until it reaches its active position.
Vehicle door lock systems in which the unlock signal is generated by actuation of a lock cylinder are known. In other known systems, this unlock signal is provided by recognition electronics in response to an infrared remote-control or radioelectric remote-control signal produced by the user using an appropriate remote control.
These known systems are not entirely satisfactory because they require the use either of a key or of a remote control, these objects taking up one of the user's hands.
This is why so-called "hands-free vehicle access" systems which do not require the use of a key or of a remote control in order to unlock the lock have been proposed. These systems are equipped with recognition electronics fitted with a radio transmitter and designed to be able to dialog with a radioelectric device incorporated into a wristwatch, a credit card, a badge or the like worn or carried by the user. The recognition electronics do not produce their unlock signal until the correct owner has been identified.
In such systems, the transmission of the unlock signal that operates the electric device, on the one hand, and the actuation of the release mechanism, on the other hand, take place simultaneously.
However, the difference between the relatively long response time of the electric device and the very short response time of the release mechanism is such that the operating member has completed its actuating movement even though it is not yet in the active position, which means that the user's first action on the door handle does not cause the door to open and that the said user has to operate the door handle again in order to open it.
This need to operate the door handle twice is a drawback that the present invention sets out to eliminate.
The subject of the present invention is therefore a motor vehicle door lock comprising: a forked latch intended to interact with a striker; a pawl which normally locks the latch in the closed position and which can adopt an "escapement" position in which it no longer acts on the said latch; a latch-release mechanism comprising an operating member, which, on the one hand, can adopt either an active position in which it acts, during its actuating movement, on the pawl to place it in the "escapement" position, or an inhibited position in which, during its actuating movement, it has no effect on the pawl and, on the other hand, may experience an actuating movement in response to actuation of the door handle by the user; and an electric device which responds at least to an unlock signal by moving the operating member from its inhibited position until it reaches its active position, characterized in that the operating member consists of a set of two links articulated together by a hinge joint, of which one of the links, known as the first link, comprises a thrust surface which is positioned in such a way that when the operating member is in the active position, the thrust surface comes up against and carries along a peg provided on the pawl, during the actuating movement of the operating member, until the said pawl has been placed in the "escapement" position, and that when the operating member is in the inhibited position, the thrust surface at most comes into contact with the said peg, during the actuating movement of the operating member so that the operating member has no action on the pawl, and of which the other link, known as the second link, is articulated to a lever for opening the lock from the outside which lever is intended to move the operating member in its actuating movement in response to actuation of the door handle by the user, and in that the aforementioned electric device comprises a lock/unlock lever cooperating with the hinge joint to make it pivot about the articulation between the second link and the lever for opening from the outside, so as to increase the distance separating the peg of the pawl from the hinge joint, therefore from the thrust surface when the operating member is moved into its inhibited position. By providing a hinge joint operating member, it is possible to reduce the number of moving parts in the lock, which makes it possible to produce a more compact lock.
In one particular embodiment, the lock/unlock lever at one end has a fork between the branches of which the hinge pin of the hinge joint is housed so that it can slide so as to allow the actuating movement of the operating member, both in its inhibited position and in its active position.
According to another feature, the lock comprises an opening catch-up means which, when the unlock signal is transmitted more or less at the end of the actuating travel of the operating member, brings the pawl into the "escapement" position, the opening catch-up means being produced as follows: since part of the thrust surface and the adjacent part of the surface of the periphery of the peg of the pawl are shaped and positioned in such a way as respectively to form a fulcrum and a pivot cooperating with one another when the operating member is more or less in the end-of-actuating-movement position, the moving of the operating member by the lock/unlock lever as far as the active position causes the peg of the pawl to be carried along, by virtue of the action of the fulcrum on the pivot, until the said pawl has been placed in the "escapement" position.
Thus, by virtue of the invention, the door can be opened by operating the door handle just once, and this is true despite the difference there is between the response time of the release mechanism, which is very fast, and that of the electric unlock device, which is slower.
According to yet another feature, the electric device comprises an electric motor for driving a movement transmission mechanism which acts on the opposite end of the lock/unlock lever to the end which cooperates with the hinge joint, this lever being articulated to a fixed pin of the lock at a point which is off-centred on the opposite side to the end co-operating with the hinge joint so as to increase the lever arm on the hinge joint side. Thus the force to be supplied by the electric motor to move the hinge joint is reduced, which makes it possible to use an electric motor that is less powerful than the one used in conventional locks.
Advantageously, in the active position the two links of the operating member are more or less aligned in the direction of the peg of the pawl and the lock/unlock lever cooperates with the hinge joint in such a way as to allow it to be moved in the said direction during the actuating movement of the operating member.
Conversely, it is possible to ensure that, in the inhibited position, the two links of the operating member form an obtuse angle between them, the hinge joint (10) being offset to the side with respect to the line passing through the peg of the pawl and the articulation between the second link and the lever for opening from the outside.
According to another feature, the first link is guided, during the actuating movement of the operating member, both in its active position and in its inhibited position, in such a way as to keep the thrust surface more or less in the direction of the peg of the pawl.
In another alternative form, the first link is guided, during the actuating movement of the operating member, both in its active position and in its inhibited position, in such a way as to keep the thrust surface aligned with the peg of the pawl and with the articulation between the second link and the lever for opening from the outside.
Advantageously, the hinge joint is a bistable articulation with two stable angular positions corresponding to the inhibited and to the active position of the operating member.
It is advantageous to ensure that the unlock signal is transmitted by recognition electronics which are electrically powered only when the user exerts action on the door handle, the said electronics then identifying an authorized user by a radioelectric transmission exchanged in accordance with an appropriate protocol with an electronic element worn or carried by the user; this avoids needless consumption of the electrical power. This can be obtained using a microswitch (or any other control system) which is normally open, closure of which is brought about by the opening action on the door handle, this operating system completing the recognition-electronics power-supply circuit.
Other features and advantages of the invention will become clear from reading the description, given hereinbelow by way of non-limiting indication, of two preferred embodiments, the description being given with reference to the appended drawing.